Method of assembling a glow discharge readout device

ABSTRACT

In a glow discharge readout, cathodes are arranged on a glass substrate in electrical isolation from a plurality of anodes also on the substrate. Contact pins sealably imbedded in the substrate contact respective anodes and cathodes. A transparent cover forms a sealed envelope encasing the anodes and cathodes within an illuminating gas atmosphere. The anodes are purposely recessed with respect to the cathodes, whereupon an electrical potential impressed between the anodes and selected cathodes will cause electrons to flow from the cathodes to the anodes, the electron stream being focused toward the surface of the glass substrate and away from the transparent envelope thereby preventing electron collision with the transparent envelope. According to the method of the present invention, cathodes are formed from particulate metal particles sintered under pressure and at a temperature below the melting point of the metal particles, but at a temperature sufficient to cause fusion of the substrate material. Upon fusion of the substrate in an inert atmosphere, the anodes, cathodes and contact pins are fused to the substrate simultaneously in a single operation. Applying molding pressure during fusion of the substrate will desirably recess the anodes from the cathodes.

United States Patent [1 1 Ahmed [111 3,818,556 June 25,1974

[ METHOD OF ASSEMBLING A GLOW DISCHARGE READOUT DEVICE [75] Inventor: Abul Abbas Mesbahuddin Ahmed,

Harrisburg, Pa.

[73] Assignee: AMP Incorporated, Harrisburg, Pa.

[22] Filed: Oct. 25, 1972 [21] Appl. No.: 300,631

[52] US. Cl 29/25.l4, 313/1095, 316/17 [51] Int. Cl. H0lj 9/00 [58] Field of Search 29/25.l3, 25.14, 25.15,

[5 6] References Cited UNITED STATES PATENTS 3,599,027 8/1971 Koshizuka et a1. 313/1095 Primary ExaminerRoy Lake Assistant Examiner-J. W. Davie Attorney, Agent, or FirmGerald K. Kita [57] ABSTRACT In a glow discharge readout, cathodes are arranged on a glass substrate in electrical isolation from a plurality of anodes also gn tlre substrate. Contact pins sealably imbedded in the substrate contact respective anodes and cathodes. A transparent cover forms a sealed envelope encasing the anodes and cathodes within an illuminating gas atmosphere. The anodes are purposely recessed with respect to the cathodes, whereupon an electrical potential impressed between the anodes and selected cathodes will cause electrons to flow from the cathodes to the anodes, the electron stream being focused toward the surface of the glass substrate and away from the transparent envelope thereby preventing electron collision with the transparent envelope. According to the method of the present invention, cathodes are formed from particulate metal particles sintered under pressure and at a temperature below the melting point of the metal particles, but at a temperature sufficient to cause fusion of the substrate material. Upon fusion of the substrate in an inert atmosphere, the anodes, cathodes and contact pins are fused to the substrate simultaneously in a single operation. Applying molding pressure during fusion of the substrate will desirably recess the anodes from the cathodes.

5 Claims, 9 Drawing Figures PATENTEI] JUNZ 5 I974 SHEU 1 0F 5 PATENTED E 5 74 SHEET R 0F 5 PATENTEDJUNZSIBH SHEET S [If 5 METHOD OF ASSEMBLING A GLOW DISCHARGE READOUT DEVICE In all prior art glow discharge display devices, sputtering of the cathodes has produced discoloration in the transparent cover of the display device. To prevent this, some prior art deivces utilize anode screens against the cover to divert away electrons and sputtered particles. Other prior art devices utilize thin film layers separating anodes and cahtodes, requiring electrons to migrate through the film toward the anodes and thus never migrate off the film toward the cover. The present invention provides a method whereby the anodes of a readout device according to the present invention are recessed from the cathodes. Electron emission thus is focused at a recessed anode away from the cover.

In the manufacture of prior art devices, several painstaking operations are required. Contact pins are imbedded in a glass substrate, and ground off flush with the substrate. Metal anodes and cathodes are then welded or brazed to corresponding contact pins establishing electrical connections. The anodes and cathodes are joined adhesively or fusibly to the substrate preventing the anodes or cathodes from lifting off the substrate. In other devices, the anodes and cathodes are silk screened on the corresponding pins. The manufacture of readout devices has heretofore required a relatively large number of operations. Accordingly there has been a need for a manufacturing process which can be performed with a minimum of operations. The present invention also relates to a method of manufacture wherein the anodes, cathodes and contact pins are joined simultaneously to a glass substrate thereby eliminating several operations heretofore required in the prior art.

In a glow discharge readout device, cathodes are arranged on a substrate of glass in electrical isolation from a plurality of anodes also on the substrate. Contact pins sealably imbedded in the substrate contact respective anodes and cathodes. A transparent cover forms a sealed envelope encasing the anodes and cathodes within an illuminating gas atmosphere. The anodes are purposely recessed with respect to the cathodes, whereupon an electrical potential impressed be tween the anodes and selected cathodes will cause electrons to flow from the cathodes to the anodes, the electron stream being focused toward the surface of the substrate and away from the transparent envelope thereby preventing electron collision with the transparent envelope. According to the method of the present invention, cathodes are fonned from particulate metal particles sintered under pressure and at a temperature below the melting point of the metal particles, but at a temperature sufficient to cause fusion of the substrate material. Upon fusion of the substrate in an inert atmosphere, the anodes, cathodes and contact pins are fused to the substrate simultaneously in a single operation. Applying molding pressure during fusion of the substrate will desirably recess the anodes from the cathodes.

It is therefore an object of the present invention to provide a method of fabricating a glow discharge readout device adhering anodes and cathodes and electrical contact pins simultaneously to a fusible glass substrate.

Another object of the present invention is to provide a method for manufacturing a glow discharge readout by simultaneously adhering anodes, cathodes and electrical contact pins to a fusible glass substrate, the cathodes being formed from particulate metal particles sintered under pressure and at atemperature below the melting point of the metal particles, whereby the metal particles are formed to a cohesive mass of individual particles bonded to the fusible substrate while in a mo]- ten state.

Another object of the present invention is to provide a method for manufacturing a glow discharge readout wherein anodes, cathodes and electrical contact pins are fused simultaneously to a fusible glass substrate, with the anodes being purposely recessed from the cathodes such that upon operation of the glow discharge readout, electron flow from the cathodes will be focused toward the recessed anodes.

Another object of the present invention is to provide a glow discharge readout having anodes purposely recessed from a plurality of cathodes arranged in a desired pattern on a glass substrate such that during operation of the glow discharge readout, electron flow from said cathodes will be focused toward the anodes and at the surface of the glass substrate and away from a transparent envelope encasing the cathodes and anodes in an illuminating gas atmosphere.

Another object of the present invention is to provide a glow discharge readout apparatus having the cathodes thereof forrned from particulate metal particles sintered under pressure and at a temperature below the melting point of the metal particles whereby the particles are formed to a cohesive mass of individual particles becoming bonded to a fusible glass substrate which is reduced to a molten state during sintering of the metal particles.

Other objects and many attendant advantages of the present invention will become apparent upon perusal of the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a fragmentary perspective of a preferred embodiment with parts in exploded configuration to illustrate the details of apparatus for fabricating a glow discharge readout device according to the present invention, and further illustrating an assembly of selected component parts of the preferred embodiment;

FIG. 2 is a plan view of an exemplary glow discharge readout device according to the present invention fabricated according to the method of the present invention and illustrated prior to receiving a sealably attached transparent cover;

FIG. 3 is an enlarged fragmentary perspective of a portion of the preferred embodiment of FIG. 2 illustrated in section generally along the line 3-3 of FIG.

FIG. 4 is a preferred embodiment of an anode pattern received against a fusible glass substrate and thereby forming component parts of the glow discharge readout apparatus according to the present invention;

FIG. 5 is a fragmentary elevation with parts illustrated in exploded configuration and in section illustrating the details of the assembly according to the preferred embodiment illustrated in FIG. 1; and

FIG. 6 is an enlarged fragmentary elevation in section illustrating the assembly shown in FIG. 5 in assembled configuration with anodes, cathodes and conductive pins fusibly secured to the glass substrate.

FIG. 7 is a fragmentary perspective of another preferred embodiment according to the present invention illustrating in composite form various alternative constructions of a readout device according to the present invention; and

FIG. 8 is a section taken generally along the line 88 of FIG. 7 illustrating the device of FIG. 7 in inverted configuration together with a modified carbon molding block.

FIG. 9 is an enlarged cross section of an alternative embodiment.

With more particular reference to the drawings, there is illustrated in FIGS. 1 and apparatus for manufacturing a glow discharge display device according to the present invention. The apparatus includes a generally rectangular molding block 1 having a recessed and continuous groove 2 in a rectangular configuration. The planar surface 4 of the molding block 1 is provided with a plurality of recesses machined therein. Some of the recesses are illustrated at 6. As more particular shown in FIG. 1, the recesses are isolated from one another and are purposely not interconnected. The recesses are also purposely arranged in a desired pattern forming the desired configuration of the glow discharge display. Any pattern may be used. However in the specific pattern as shown in FIG. 1, the recesses are arranged to provide a plurality of alpha numeric configurations in order to provide an alpha numeric glow discharge display. As more particularly shown in FIG. 5, the recesses 6 are substantially filled with particles of a suitable cathode material. For example, one suitable cathode material is elemental nickel in particulate form sufficient to pass through a size 320 mesh. Other suitable cathode material in particulate form may be used. The particulate material is compacted into each of the recesses 6 of the moldingblock l. The'particulate cathode material is thereby distributed in the individual recesses 6 and will form the cathodes of the glow dischargereadout apparatus in a manner to be described hereinafter. A frame 9 of fusible glass material is located in the groove 2. To form the required anodes of the glow discharge readout device, reference will be made to FIGS. 1 and 5. As shown in the figures, a pattern of anodes is illustrated generally at 10. In the preferred embodiment of the invention illustrated in FIG. I, the pattern of anodes is fabricated from a stamped and formed metal grid. As shown in FIGS. 1 and 5, the

metal grid is generally rigid and is placed in overlying relationship with respect to the recesses 6 containing the particulate cathode material 8. The actual configuration of the pattern of anodes is more particularly illustrated in FIG. 2 at 10. The overlying relationship of the anode pattern 10 with respect to the particulate cathode material 8 is also illustrated in the figure. As shown in FIG. 5, the stamped and formed metal pattern of anodes includes a plurality of integral contact pins projecting therefrom. One of the contact pins is illustrated at 12. To complete the assembly as illustrated in FIGS. 1 and 5, a plurality of fusible glass bricks 14 are stacked together to form a fusible glass substrate. The bricks are placed in overlying relationship with the pattern of anodes 10 received thereagainst. The integral contact pins 12 of the pattern of anodes are correspondingly received in apertures 16 provided through the bricks 14. The substrate fonned by the bricks 14 is impressed directly over the frame 9 and the metal particles 8 contained within the corresponding recesses 6 of vided in the bricks, some of which apertures are illustrated at 18. The additional apertures 18 receive therethrough corresponding metal contact pins, some of which are illustrated at 20. As shown more particularly in FIG. 6, the contact pins 20 are partially imbedded in the particulate cathode material 8 located in the grooves 6 of the molding block 1. In addition, each of the bricks 14 includes a relatively enlarged diameter aperture generally illustrated'at 22. A selected one of the apertures 22 receives therein a metal tube 24, the purpose of which will be described hereinafter.

With reference to FIGS. 1, 5 and 6, there is further provided an inverted molding block 26 of carbon having an inverted planar surface 27 impressed over the fusible glass substrate formed by the plurality of bricks 14. The inverted molding block includes an inverted encircling rim 28 which registers around the periphery of the substrate formed by the plurality of stacked bricks 14. As shown in FIG. 6, taken in conjunction with FIGS. 1 and 5, the molding block 26 includes a plurality of apertures some of which are shown at 30 receiving corresponding pins 20 and 12 therein and aligning the pins in parallel fashion when the molding block 26 is impressed over the fusibls glass substrate formed by the plurality of bricks 14. In addition the molding block 26 includes a relatively enlarged aperture 32 receiving the metal tube 24 therein, maintaining it in parallel alignment with the pins 20 and 12. As shown in FIG. 6, the weight of the molding block 26 over the bricks 14 applies a molding pressure when the assembly is heated for approximately 18 minutes in a :10 percent hydrogen and nitrogen atmosphere at a temperature of l,860F. The bricks 14 are Coming Glass Company 90l3 type, fusible glass in powder form compacted to make the individual bricks l4 and the frame 9. Heating at 1,860F occurs at a temperature below the melting point of the nickel particles of the cathode material 8 but at a temperature sufficient to fuse the glass material forming the bricks l4 and the frame 9.-The described heating cycle will fuse the particles of the fusible glass bricks 14- to form a continuous rectangular substrate as shown in FIG. 2 generally at 32. In addition, the substrate will be substantially nonporous and will fuse in encirclement about the pins 12 and 20 and the metal tube 24. The pins and the tube are advantageously selected from 52:48 percent nickel and iron so as to have a coefficient of expansion compatible with that of the fusible glass particles of the bricks 14. During the heating cycle the particles of the fusible glass will bond sealably in encirclement around the pins and tube without voids being created by differential expansion.

A particular feature according to the present invention resides in the fact that the fusible glass particles in a molten or melted state will flow down into the recesses 6 and become bonded to the particulate cathode material 8 in the recesses. The same flowing action will also fuse the frame 9 unitarily to the substrate 32 and will cause the apertures 22 to disappear or close up during flowing of the glass substrate in the heating or firing operation. With reference to FIGS. 2 and 3, the invention will be further described in detail. After the heating cycle is completed, the assembly is cooled to room temperature and the molding blocks 1 and 26 removed. As shown in FIG. 3, the flowing of the fusible glass into the recesses 6 during the firing operation forms projecting platforms or projections which are generally trapezoidal in cross section, the metal particles 8 being bonded to the projections or platforms upon partial diffusion of the particles into the glass forming the platforms. In addition, the glass when solidified holds the individual particles of each recess into a cohesive mass, compressing the particles of the cohesive mass in compression with one another in mechanical and electrical contact. The particles 8 are thereby sintered at a temperature below their melting point during the heating operation and are electrically in contact with each other and held in place by the fusible glass forming the platforms or projections 34. If desired, the cathode particles 8 may be arranged to form a plurality of alpha numeric readout patterns as shown in FIG. 2. Also additional particles of cathode material may be arranged and formed by the sintering process into a desired pattern representing a period and comma as shown at 8. As shown in FIG. 3, still additional anode particles may be arranged and formed into a minus sign as shown at 8". The pattern of metal particles 8, 8' and 8" thereby form the cathodes of the glow discharge readout device according to the present invention. As shown in FIG. 3 the pattern of anodes 10 includes loop portions 36 respectively surrounded by selected cathodes formed by the cathode material 8. Such loop portions 36 are interconnected by anode bridging portions 38 connecting the loop portions 36 to the remaining part of the pattern of anodes externally of the selected encircling cathodes. The cathodes are electrically isolated from the anode bridging portions 38 by the fusible glass substrate which has flowed into the recesses 6 of the molding block 1 during the firing operation to form the raised platforms or projections 34. Thus during formation of the platforms 34 by flowing of the fusible glass material, the flowing glass also operates to electrically isolate the cathodes from the bridging portions 38 of the anodes which become imbedded in the glass forming the resulting platfomis 34. Also during the firing operation, the pattern of anodes 10 becomes fusibly adhered to the molten surface of the glass substrate 32 during the firing operation. To complete the glow discharge readout according to the present invention, a conventional transparent glass cover (not shown) is adhered to the frame 9 in a conventional manner, such as by utilizing a fusible sealant and bonding agent between the glass cover and the frame 9. This encases the anodes and cathodes within a transparent hermetically sealed envelope. The space within the envelope is defined between the surface of the substrate 32 and the transparent window. The space is then evacuated and backfilled with a suitable illuminating gas according to techniques well known in the prior art. Evacuation of the envelope space and introduction of sealing gas may be introduced through the metal tube 24 which may be advantageously sealed after introduction of the illuminating gas into the envelope space. The projecting pins 12 and 20 may be advantageously connected to a printed circuit board, or

to a printed circuit silk screened directly on the exterior planar surface of the substrate 32. The specific type of printed circuit which is on a separate board or silk screened to the substrate is of conventional design and is thus not illustrated. However the present invention is readily suited for silk screening the printed circuit directly to the exterior surface thereof in contact with the pins 20 and 12.

As another feature according to the present invention, the anode portions 36 are purposely recessed with respect to the cathodes formed by the cohesive mass of particles 8 forming the cathodes. In operation, a voltage is impressed across the anodes and selected cathodes to produce a desired alpha numeric glow discharge readout in the conventional manner. However since the anode portions 36 as well as the remaining anode portions of the pattern 10 are recessed with respect to the cathodes, the electron stream will be directed from the cathodes downwardly toward the surface of the substrate 32 and will be focused at the recessed anode portions on the surface of the substrate. The electron stream or flow will thereby be directed away from the transparent window preventing discoloration thereof by stray electron bombardment. The trapezoidal shape of the platforms 34 will allow flow of electrons along the shortest possible path from the cathodes to the anode portions without collision with, or migration through, the fusible glass forming the platforms 34. Such action thereby insures a maximum foot- Lambert brightness of the glow discharge. Further to increase the foot-Lambert output of the glow discharge, each of the cathodes is formed by cathode material which is of separate particle form. The separate particles although in a cohesive mass as described give the cathodes a very rough surface having projecting portions formed by individual particles and valleys or crevices formed between irregular surfaces of adjacent abutting particles. When electrons are emitted from the surfaces of the selected cathodes some are emitted from the crevices so as to collide with one another and with the protruding particles of the cathodes to create an electron bombardment or cascading effect, further inducing additional electron emission and increasing the foot-Lambert output of the glow discharge. The rough surface also reduces tendency of the cathode material to sputter away from the crevices which trap the sputtered material.

FIG. 4 illustrates a modification, wherein the bricks 14 of the embodiment of FIGS. 1-3, 5 and 6, are replaced by a substituted unitary plate 40 of fusible ceramic or glass material similar to the bricks 14. The substituted plate 40 thus provides a substrate on which the anodes and cathodes are adhered during the described sintering and heating operation. As shown in FIG. 4, the pattern of anodes 10 may be placed against the substrate prior to the heating process. Since the substrate is unitary, the anode pattern may be silk screened directly to the surface without a need for a formed metal pattern of anodes as required in the embodiment of FIGS. 1-3.

Another way to recess the anodes would be to create depressions in the substrate during the molding process. This can be accomplished by depressing the glass substrate by the carbon molding block during the heating operation. This will depress the anodes with respect to the cathodes.

As shown in FIG. 7, a modification of the readout device is generally indicated at 40. The glass substrate 42 is provided with a plurality of cathodes 44 deposited directly on the surface of the substrate by a cohesive mass of particulate metal adhered to the surface of the substrate 42 by a sintering process similar to that as previously described. Accordingly the formed cathodes 44 are adhered directly to the surface of the substrate 42, rather than on projecting portions as heretofore described in the embodiment illustrated in FIGS. 1-5. Since the invention is directed toward recessing the anodes with respect to the cathodes, reference is made to FIGS. 7 and 8 wherein recesses 46 are each provided with anode portions 48 similar in configuration to the rectangular or round configuration of the recesses Q6. The recesses 46 may be of any desired configuration. As shown in FIGS. 7 and 8, the substrate 42 is provided with a plurality of contact pins t therein which are assembled to the substrate in a manner similar to the assembly of the embodiment previously described in conjunction with FIGS. 1-5. The pins 50 contact respectively the anode portions 48 and the cathode portions 44. In this embodiment it is understood that each anode portion 43 is provided with its own contact pin 50, rather than being interconnected by anode bridging portions which are incorporated into the preferred embodiment of FIGS. 1-5. As shown in FIG. 8 a carbon molding block 52 is utilized which has a tapered projecting portion 46 having a recess portion 48' therein. In addition, the molding block 42 has a planar surface 54 from which the projecting portion 46 protrudes. The planar surface 54 has a plurality of recesses 44 therein which are of the same configuration as the desired cathode portions 44 of the preferred embodiment 40. With reference to FIG. 8, the glass substrate 40, with the pins 50 assembled therein, is compressed over the carbon block 52. In the version as shown, the anode portions 48 and the cathode portions 44 may be deposited upon the glass substrate so which is preformed with the recess 46. For example the anode portions 48 and cathode portions 44 may be deposited by silk screening a quantity of discrete metal particles in a binder which sublimes during sintering at elevated temperatures. The assembly is then placed in registration over the carbon block 52, with the recess portions 44' of the carbon block receiving the cathode portions 44 therein, and with the recess portion 48' of the carbon bit. :24 receiving the cathode portion 48 therein. The assembly is then provided thereover with the carbon block 26 which was utilized in the fabrication of the preferred embodiment discussed in conjunction with FIGS. l-S. The assembly is then sintered to simultaneously adhere the metal particles of the anode portions 48 and the cathode portions 44 into a coherent mass of individual particles to provide anodes and cathodes having the same characteristics as those resulting from the fabrication of the preferred embodiment discussed in conjunction with FIGS. 1-5. The configuration of the carbon block 52 with its recessed portions 44 and 48 and its projecting portion 46' will mold the fusible glass of the substrate 40 to the desired configuration having recessed anodes, which configuration is shown in FIG. 7. In addition the sintering process fusibly and sealably adheres the anode portions 48, the cathode portions 44 and the pins 50 sealably to the substrate 40. The substrate 40 includes a projecting frame 56 to which the transparent window is sealably attached. The frame is formed by flowably conforming the fusible glass to a continuous recess 56 of the molding block 52.

As an alternative way of fabricating the preferred embodiment shown in FIG. 7, metal particles forming the anodes and cathodes may be first deposited in the recesses 44/ and 48' of the carbon block 52. The fusible glass substrate 40 then may overlie the carbon block 52 with the pins 50 being assembled within the fusible substrate and in contact with the respective anodes and cathodes. In this alternative fabrication technique, the fusible glass substrate 40 need not be preformed with the recesses 46. Instead, during the sintering operation, the glass will be reduced to a fusible state and will flowably conform itself to the configuration of the carbon molding block 52. The recesses 46 containing the resultant anodes 48 will thus be formed in the fusible glass substrate and the anodes and cathodes will adhere to the glass, without a need for preforming the substrate prior to the sintering process;

In each of the preferred embodiments, the glass substrate sealably adheres to the contact pins to provide hermetic seals encircling the pins. In many prior art devices, the methods of assembly do not lend themselves to providing a hermetic seal in encirclement around each of the contact pins. The glass substrate of a prior art device must then be encapsulated within a glass envelope such as an electron tube. In the present invention, the glass substrate itself, together with the transparent cover plate serves as the envelope receiving the illuminating gas therein. This obviates the need for assembling the device within an electron tube.

As shown in FIG. 7, each alpha numeric character may be separated from an adjacent one on the substrate 42 by either a recessed barrier 58 or a projecting barrier 60 formed by a corresponding molding portion 58 and 60 on the carbon molding block 52 which form the substrate 4G? with the barriers 58 and 60 during the molding operation as described. The barriers 58 and 60 provide a lengthened effective surface area between adjacent alpha numeric characters, thereby lengthening the bridging path between adjacent characters. The increased bridging path prevents the possibility of shorting between adjacent alpha numeric characters which might be caused by sputtered cathode material scattered upon the bridging path and causing an electrical connection between adjacent alpha numeric characters. Either a recessed barrier 99 or projecting barrier 9 may also be provided between the segments 44 of each display character, which barriers are similar to the barriers 58 and 60.

FIG. g is an enlarged cross section of an alternative using carbon molding blocks 101, 1102, 1103 and 104. Recess I06 receives glass to form the frame 56. Glass preforms M are placed between blocks Hill and 102. The contact pins 20 are held in corresponding apertures of block Hill. The cathode portions 44 are silk screened on the surface 108 of block 102. Block 103 has projections llltl which protrude through block 102. The anodes 48 are sill; screened on the ends of the projections llltl. When the assembly is slightly compressed, the projections l 10 will protrude from the surface 108. The glass preforms 14 will flow around the projections III) and will thereby form the recesses 46 as shown in the embodiment of FIG. 7. The anodes 48 and cathodes 44 will adhere to the retlowed glass and will transfer from the carbon blocks 102 and 103.

Although preferred embodiments and modifications of the present invention have been shown and described in detail, other embodiments and modifications of the present invention are intended to be covered in the spirit and scope of the appended claims, wherein:

I claim:

1. A method of making a glow discharge readout device, comprising the steps of: providing metal particles compacted within selectively arranged recesses of a molding block, providing a pattern of anodes against a fusible glass substrate, overlying said substrate over the metal particles, locating a plurality of contact pins through the glass substrate at selected locations for imbedding within corresponding metal particles within said selected recesses, applying heat uniformly to said assembly of the glass substrate and metal particles at a temperature below the melting point of said metal particles but at a temperature sufficient to melt said glass substrate, bonding said anodes and said metal particles to said substrate in a melted state, bonding said metal particles to said glass substrate by partial diffusion into said substrate in a molten state, forming projecting platforms on said substrate by flowing portions of said substrate into projecting configurations while in a melted state, bonding said metal particles to said projecting platforms, compressing said metal particles into mutual mechanical and electrical engagement to form a cohesive mass of particles fixedly bonded to the platforms formed on said substrate, removing said molding block from said assembly, and encasing said anodes and said metal particles in a sealed transparent envelope containing a glow discharge gaseous atmosphere.

2. The method as recited in claim 1, wherein, said step of providing a pattern of anodes against the substrate comprises the step of: silk-screening the pattern on the surface of said substrate.

3. The method as recited in claim 1, wherein said step of providing a pattern of anodes against a substrate comprises the steps of: overlying a formed metal grid in the configuration of said pattern of anodes against said substrate, and interposing said pattern between said substrate and said metal particles.

4. The method as recited in claim 3, and further including the step of: flowing portions of said substrate while in a molten state into interposed relationship between said pattern of anodes and said metal particles to electrically isolate the pattern from the metal particles and to form said projecting platforms on which said metal particles are bonded.

5. A method of making a glow discharge readout device, comprising the steps of:

providing a fusible glass substrate, locating a plurality of contact pins through said substrate, providing metal particles compacted within selectively arranged recesses of a molding block, pressing said molding block against said fusible glass substrate with said metal particles against said substrate surface, applying heat uniformly to said substrate at a temperature sufficient to flow said substrate but below the melting point of said metal particles and said contact pins, partially penetrating protruding portions of said molding block into said substrate while said substrate is in a molten state to form a plurality of depressions in said substrate surface, 7 bonding said metal particles to said substrate surface by partial diffusion of said metal particles into said substrate while said substrate is in a molten state to form a plurality of cathodes and to form anode means within said depressions, said anode means and said cathodes being bonded to the substrate surface and in electrical contact with said contact pins, bonding said substrate in encircling relationship with said contact pins while said substrate is in a molten state, solidifying said substrate an amount sufficient to permit removal of said molding block, removing said molding block from said substrate, and

cathodes within a glow discharge gaseous atmosphere. 

1. A method of making a glow discharge readout device, comprising the steps of: providing metal particles compacted within selectively arranged recesses of a molding block, providing a pattern of anodes against a fusible glass substrate, overlying said substrate over the metal particles, locating a plurality of contact pins through the glass substrate at selected locations for imbedding within corresponding metal particles within said selected recesses, applying heat uniformly to said assembly of the glass substrate and metal particles at a temperature below the melting point of said metal particles but at a temperature sufficient to melt said glass substrate, bonding said anodes and said metal particles to said substrate in a melted state, bonding said metal particles to said glass substrate by partial diffusion into said substrate in a molten state, forming projecting platforms on said substrate by flowing portions of said substrate into projecting configurations while in a melted state, bonding said metal particles to said projecting platforms, compressing said metal particles into mutual mechanical and electrical engagement to form a cohesive mass of particles fixedly bonded to the platforms formed on said substrate, removing said molding block from said assembly, and encasing said anodes and said metal particles in a sealed transparent envelope containing a glow discharge gaseous atmosphere.
 2. The method as recited in claim 1, wherein, said step of providing a pattern of anodes against the substrate comprises the step of: silk-screening the pattern on the surface of said substrate.
 3. The method as recited in claim 1, wherein said step of providing a pattern of anodes against a substrate comprises the steps of: overlying a formed metal grid in the configuration of said pattern of anodes against said substrate, and interposing said pattern between said substrate and said metal particles.
 4. The method as recited in claim 3, and further including the step of: flowing portions of said substrate while in a molten state into interposed relationship between said pattern of anodes and said metal particles to electrically isolate the pattern from the metal particles and to form said projecting platforms on which said metal particles are bonded.
 5. A method of making a glow discharge readout device, comprising the steps of: providing a fusible glass substrate, locating a plurality of contact pins through said substrate, providing metal particles compacted within selectively arranged recesses of a molding block, pressing said molding block against said fusible glass substrate with said metal particles against said substrate surface, applying heat uniformly to said substrate at a temperature sufficient to flow said substrate but below the melting point of said metal particles and said contact pins, partially penetrating protruding portions of said molding block into said substrate while said substrate is in a molten state to form a plurality of depressions in said substrate surface, bonding said metal particles to said substrate surface by partial diffusion of said metal particles into said substrate while said substrate is in a molten state to form a plurality of cathodes and to form anode means within said depressions, said anode means and said cathodes being bonded to the substrate surface and in electrical contact with said contact pins, bonding said substrate in encircling relationship with said contact pins while said substrate is in a molten state, solidifying said substrate an amount sufficient to permit removal of said molding block, removing said molding block from said substrate, and sealing a transparent window to at least portions of said substrate to contain said anode means and said cathodes within a glow discharge gaseous atmosphere. 